Ed. note: We've covered the homemadeairconditioner territory before on Lifehacker, but HackCollege's Kelly Sutton offers this awesome video guide to the DIY, dorm-legal air conditioner to help students (or anyone trying to save a few bucks) stay cool.

Many campuses have strict policies regarding portable air-conditioners. Because A/C ain't cheap, schools worry that students would overcool their rooms and increase the electricity bill (after all, you don't pay utilities for your dorm room)—or maybe admins are worried about improperly affixed units falling off the sides of buildings. Either way, some campuses are unbearably hot during the earlier parts of fall and give students no way to remedy the situation. Until now.

When you have no other option, just build it yourself

Believe it or not, it's possible to build your own air conditioner for about $40. Well technically, it's not an air conditioner; it's more of a heat-concentrator. It will cool even the hottest dorm room to a nippy 60 degrees Fahrenheit in no time. To get started, you'll need to make a trip to the hardware store.

You will be building a unit that absorbs heat into some water, allowing you to quickly dispose of that water outside.

Materials

Instructions

Detach the face of the fan and put it on your work bench or table.

Grab your zip-ties and copper tubing. Start coiling the copper tubing around the face of the fan. Use the zip-ties about every 6 inches to attach that section to the fan face. Make sure that both ends shoot out the bottom of the fan's face.

Take your hose clamps and secure the rubber tubing onto either end of the copper tubing. If you need to cut your copper tubing, don't forget to sand the edges before you start working with the tubing. Freshly cut copper is very sharp.

Fill up one of your buckets with water.

Position the bucket full of water on a ledge or a desk—someplace above ground level.

Siphon the water through the contraption to the bucket on the floor. (Bernoulli's Principle in action!)

Turn on the fan.

After a few minutes, all of the water will drain into the bucket on the floor. You can now dispose of this lukewarm bucket as you see fit. Repeat a few times to get your room extra chilled.

Many ways to skin a cat

This is just one way of creating a dorm room cooling device. You can also create something more akin to a "swamp cooler" if you're looking for something a tad simpler. A swamp cooler is just a device that usually just moves air over a body of water to aid in evaporation and spreading the chill. This isn't so great if you're looking to keep the humidity down.

Or you can always just seek inspiration from Mr. Freeze.

The school-bound productivity nuts at weblog HackCollege will be joining us all week to offer their perspective on making the most of your Back to School regimen.